CAUSES OF BREAST CANCER

When you're told that you have breast cancer, it's natural to wonder what may have caused the disease. But no one knows the exact causes of breast cancer. Doctors seldom know why one woman develops breast cancer and another doesn't.
Doctors do know that bumping, bruising, or touching the breast does not cause cancer. And breast cancer is not contagious. You can't catch it from another person.
Doctors also know that women with certain risk factors are more likely than others to develop breast cancer. A risk factor is something that may increase the chance of getting a disease.
Some risk factors (such as drinking alcohol) can be avoided. But most risk factors (such as having a family history of breast cancer) can't be avoided.
Studies have found the following risk factors for breast cancer:

• Age: The chance of getting breast cancer increases as you get older. Most women are over 60 years old when they are diagnosed.
• Personal health history: Having breast cancer in one breast increases your risk of getting cancer in your other breast. Also, having certain types of abnormal breast cells (atypical hyperplasia, lobular carcinoma in situ [LCIS], or ductal carcinoma in situ [DCIS]) increases the risk of invasive breast cancer. These conditions are found with a breast biopsy.
• Family health history: Your risk of breast cancer is higher if your mother, father, sister, or daughter had breast cancer. The risk is even higher if your family member had breast cancer before age 50. Having other relatives (in either your mother's or father's family) with breast cancer or ovarian cancer may also increase your risk.